National Centers Coastal Ocean Science (NCCOS) Monitoring: Six-minute water level, temperature, and salinity data from Marine Corps Base Camp Lejeune (MCBCL), Jacksonville, NC, 2008-02-21 to 2018-11-06 (NCEI Accession 0203764)

Methods: Six Yellow Springs Instrument (YSI) 600LS vented sondes were interchanged approximately every 5 months at each station. Sonde data were downloaded every 1-2 months and compiled for each sonde deployment. Sondes were calibrated prior to deployment, checked for drift post-deployment, and serviced regularly by YSI. Some drift in water level calibration did occur, contributing to systematic error over the deployment and random error over the time series. Drift in time occurred most frequently, with a gain or loss of 1-2 minutes over a deployment. Water level data recorded relative to the sonde depth were adjusted to m NAVD88 using methods described in Hilting et al., 2019. The compiled deployment data of each secondary station were compared to each other and to the National Water Level Observation Network (NWLON) station in Beaufort, NC, (#8656483) for consistency in their relative trends. This comparison helped identify the exact timing of a shift in sensor elevation due to a boat strike, for example, and decoupling of the exterior pipe and the backing board (Hilting et al., 2019). Data with uncertain sensor elevation were removed. Large gaps (> 3 hrs) in the record also resulted from battery failures or sensor malfunction. Once reviewed for quality control, the water level data from each sonde deployment at each station were compiled into a master database and gaps < 3 hours and offsets from the exact 6-minute interval were linearly interpolated.

Water level data were collected from May 15, 2008, to August 26, 2016, at Gottschalk Marina Wallace Creek (GMWC) (8.3 years) with a gap of 6 days starting May 27, 2016. Continuous data span a full 8 years at GMWC. There was a 6-day gap (5/27/16-6/2/16) at GMWC in water level data due to instrument failure or disturbance. At Mile Hammock Bay (MHB), where eight gaps of 7 to 61 days occurred between February 21, 2008, and November 6, 2018 (10.7 years of data collection), the longest continuous record was from February 27, 2013, to December 24, 2016 (1396 days or 3.8 years). There were eight large gaps (7-84 days duration) at MHB in water level data due to instrument failure or disturbance: 2/29/08-4/10/08, 6/22/09-7/31/09, 10/20/11-12/7/11, 2/14/13-2/27/13, 12/24/2016-1/4/2017, 1/28/2017-3/30/2017, 8/2/2018- 8/9/2018, and 9/10/2018-9/26/2018. Temporal gaps in the water salinity and water temperature data were not interpolated but adjustments were made to the recorded date and time to by adding or subtracting up to 2 minutes in order to provide data on the exact 6 minute increment. Both the original recorded date and time, and the adjusted date and time are provided. For detailed methodology see Hilting et al., 2019.

A summary of the number of gaps of different periods of duration in the record is in Table 1. The start time and duration of gaps > 3 hours in MHB and GMWC water temperature and water salinity are provided in Table 2. Table 1: Water Temperature and Salinity Data Gap Summary Gap Duration Station Temperature Gaps (n) Salinity Gaps (n) < 1 hour MHB 92 89 1-3 hours MHB 18 16 > 3 hours MHB 7 8 Total # gaps MHB 117 113 < 1 hour GMWC 66 67 1-3 hours GMWC 11 11 > 3 hours GMWC 2 2 Total # gaps GMWC 79 80 Table 2: Water Temperature and Salinity Data Gaps Greater than 3 Hours Gap start time (EST) Station Gap > 3 hours duration (days) Temperature Salinity 2/29/2008 11:18 MHB 41.2 x x 5/9/2012 8:12 MHB 113.1 x 2/14/2013 5:42 MHB 13.4 x x 9/10/2014 13:06 MHB 0.1 x x 12/24/2016 22:24 MHB 10.6 x x 1/28/2017 12:24 MHB 59.9 x x 10/12/2017 8:48 MHB 53.3 x x 8/2/2018 19:48 MHB 6.6 x x 9/4/14 13:24 GMWC 0.2 x x 6/2/16 14:42 GMWC 6.3 x x

Submission Package ID: 2DUAPU